Thin film solar modules are typically made from a plurality of individual solar cells which are connected with one another in series. Therefore the total current of the module corresponds to the current from an individual solar cell, whereas the idle voltages of the solar cells essentially add to one another in the series connection. In order to obtain an output power that is as high as possible the solar cells have to be configured narrow since then losses based on low surface conductivities of the contact layers and series resistances are minimized. An embodiment for a thin film solar module of this type is disclosed in JP 2001-111083A. Therein particular sub-modules are described that are configured from solar cells that are connected with one another in series, wherein the sub-modules in turn are also connected with one another in series.
However, when a large number of solar cells are connected in series which is the case when the module is divided into many narrow solar cells, the module generates very high voltage and very low current. High voltages, however, are unsuitable for using thin film solar modules in photovoltaic systems and render these uneconomical. In a simple thin film solar module a compromise between a solar cell width and module voltage has to be made wherein typically the full power yield of the solar cells is not achieved.
In order to reduce the module voltage of the solar module identical sub modules made from solar cells that are connected in series are connected in parallel with one another. Thus, two collecting conductors or cell contact bands are required for each sub module, one respective cell contact band for contacting the first (positive) and the last (negative) in a series of solar cells connected in series. All positive and negative cell contact bands are then combined into a module exterior connector where the generated power is tapped from the outside.
U.S. 2009/0260671 describes a thin film solar module with plural sub modules which are connected in parallel with one another. Thus, the parallel connection is performed through a shared photovoltacially inactive solar cell. A photovoltacially inactive solar cell in each sub module, however, leads to lower overall light yield for the thin film solar module.
U.S. 2008/0142070 A1 follows a similar path. The thin film solar module described therein is also assembled from sub modules which are connected in parallel through shared solar cells at the sub module ends or sub modules edges. However, herein, the number of inactive solar cells is reduced over U.S. 2009/0260671. The shared solar cells which are active, however, differ from the remaining solar cells. They therefore have to be adapted to the remaining solar cells in order to be connectable in series with the remaining solar cells which requires additional method steps. The solar cell module disclosed in JP2005-353767A also includes sub modules that are connected in parallel with one another through shared solar cells that differ from the remaining solar cells.
On the other hand side JP2000-049369A describes a thin film solar module assembled from plural sub modules in which the sub modules are connected with one another through solar edge cells in alternating polarization. The connection of the sub modules is thus provided through shared bus bars which reach into the layers of the thin film solar module to the front side electrode. This requires an additional method step for forming the bus bars. Additionally valuable solar module surface between the sub modules is wasted for the bus bars, wherein the surface is then not available any more for the active semiconductor layer.
Solar cell modules are known from DE 101 643 A1, JP 2004-327 901 A, JP 2003 152 211 A and JP 07 297 436 in which sub modules are separated from one another in a first step through breaking and the sub modules are then applied in a subsequent step to a shared substrate for producing the solar cell module.
A solar cell module is known from U.S. Pat. No. 4,315,096 in which the sub modules are not separated from one another through breaking but are monolithically produced through a structuring process. U.S. Pat. No. 5,593,901A and JP 61 073 386 A also show monolithically configured thin film solar modules.